1. Field of the Invention
The present invention relates to an electronic endoscope.
2. Description of the Prior Art
In the medical field, for example, electronic endoscope systems have been used as diagnostic systems for examining internal portions (e.g., the alimentary canal) of the human body.
In general, such electronic endoscope systems include a light source device and an electronic endoscope which is removably mounted (connected) to the light source device.
FIG. 11 is a bottom view and a cross-sectional view of a tip portion of the prior-art electronic endoscope.
As shown in FIG. 11, the prior-art electronic endoscope 100 includes an endoscope main body 110. In a tip portion 120 of the endoscope main body 110, there are provided a CCD imaging sensor (imaging element) 130 and a pair of light-emitting diodes (light-emitting elements) 140 for emitting light toward an observation part of a patient.
In this prior-art electronic endoscope 100, these light-emitting diodes 140 are arranged at the opposite sides of the CCD imaging sensor 130 as shown in FIG. 11.
Further, in front of the CCD imaging sensor 130, there is provided an imaging optical system that includes an objective lens 150 and convex lenses 160 and 170.
Furthermore, a diverging lens (light distribution lens) 180 is provided in front of each of the light-emitting diodes 140.
However, in the prior-art electronic endoscope 100 the light-emitting diodes 140 are arranged at the opposite sides of the CCD imaging sensor 130, and this results in a problem that the diameter of the endoscope main body 110 of the electronic endoscope 100 becomes large.
Therefore, it is an object of the present invention to provide an electronic endoscope provided with an endoscope main body that has a relatively small diameter.
In view of the object, the present invention is directed to an electronic endoscope having a tip portion with a tip end which is to be inserted into an object to be observed, the electronic endoscope comprising:
an imaging element provided in the tip portion;
an imaging optical system having an optical axis, the imaging optical system being provided in the tip portion at a position closer to the tip end than the imaging element; and
a light-emitting element for emitting light toward an observation part of the object, the light-emitting element being provided in the tip portion at a position closer to the tip end than the imaging element, wherein the light-emitting element is arranged such that at least a part of the light-emitting element is seen so as to overlap with the imaging element when viewed from the optical axis direction of the imaging optical system.
According to the present invention described above, the light-emitting element is provided in the tip portion at a position closer to the tip end then the imaging element. In addition, the light-emitting element is arranged such that at least a part of the light-emitting element is seen so as to overlap with the imaging element when viewed from the optical axis direction of the imaging optical system. As a result of this arrangement, it becomes possible to reduce the diameter of the electronic endoscope, in particular, the diameter of the tip portion of the electronic endoscope. Further, when such an electronic endoscope that has a small diameter is used as a medical endoscope, it becomes possible to relieve the pain that patients may feel during diagnosis.
In this invention, it is preferred that the imaging element has an imaging region that includes at least one shading region for detecting a reference level of optical black, in which the light-emitting element is arranged so that at least a part of the light-emitting element is seen so as to overlap with the shading region of the imaging element when viewed from the optical axis direction of the imaging optical system.
Further, in this invention, it is also preferred that the imaging optical system includes a light-deflecting member for deflecting light rays from the observation part of the object. In this case, it is preferred that the imaging element has an imaging region that includes at least one shading region for detecting a reference level of optical black, in which the light-emitting element is arranged such that at least a part of the light-emitting element is situated within the region of light rays being directed to the shading region of the imaging element.
Furthermore, in this invention, it is also preferred that the imaging element has an imaging region that includes an effective imaging region on which an image is to be formed by light rays that have passed through the imaging optical system.
Moreover, in this invention, it is also preferred that the light-emitting element includes a light-emitting diode.
Another aspect of the present invention is directed to an electronic endoscope having a tip portion with a tip end which is to be inserted into an object to be observed, the electronic endoscope comprising:
an imaging element provided in the tip portion;
an imaging optical system having an optical axis, the imaging optical system being provided in the tip portion in front of the imaging element along the optical axis; and
a light-emitting element for emitting light toward an observation part of the object, the light-emitting element being provided in the tip portion at a position closer to the tip end than the imaging element, wherein the light-emitting element is arranged such that at least a part of a projected image which could be formed by projecting the light-emitting element onto a projecting surface perpendicular to the optical axis of the imaging optical system overlaps with a projected image which could be formed by projecting the imaging element onto the projecting surface perpendicular to the optical axis.
In this invention, it is preferred that the imaging element has an imaging region that includes at least one shading region for detecting a reference level of optical block, in which the light-emitting element is arranged such that at least a part of a projected image which could be formed by projecting the light-emitting element onto the projecting surface perpendicular to the optical axis overlaps with a projected image which could be formed by projecting the imaging region of the imaging element onto the projecting surface perpendicular to the optical axis.
Further, in this invention, it is also preferred that the electronic endoscope further comprises a light-deflecting member for deflecting light rays emitted from the light-emitting element, wherein the light-deflecting member is provided in front of the light-emitting element.
Further, in this invention, it is also preferred that the imaging optical system includes a light-deflecting member for deflecting light rays from the observation part of the object.
Moreover, in this invention, it is also preferred that the imaging element has an imaging region that includes an effective imaging region on which an image is to be formed by light rays that have passed through the imaging optical system.
Still further, in this invention, it is also preferred that the light-emitting element includes a light-emitting diode.
Yet another aspect of the present invention is directed to an electronic endoscope having a tip portion with a tip end which is to be inserted into an object to be observed, the electronic endoscope comprising:
an imaging element provided in the tip portion;
an imaging optical system having an optical axis, the imaging optical system being provided in the tip portion at a position closer to the tip end than the imaging element; and
a plurality of light-emitting elements for emitting light toward an observation part of the object, each of the light-emitting elements being provided in the tip portion at a position closer to the tip end than the imaging element, wherein each of the light-emitting elements is arranged such that at least a part of the light-emitting element is seen so as to overlap with the imaging element when viewed from the optical axis direction of the imaging optical system
Yet another aspect of the present invention is directed to an electronic endoscope having a tip portion which is to be inserted into an object to be observed, the electronic endoscope comprising:
an imaging element provided in the tip portion;
an imaging optical system having an optical axis, the imaging optical system being provided in the tip portion in front of the imaging element along the optical axis; and
a plurality of light-emitting elements for emitting light toward an observation part of the object, each of the light-emitting elements being provided in the tip portion at a position closer to the tip end than the imaging element, wherein each of the light-emitting elements is arranged such that at least a part of a projected image which could be formed by projecting the light-emitting element onto a projecting surface perpendicular to the optical axis of the imaging optical system overlaps with a projected image which could be formed by projecting the imaging element onto the projecting surface perpendicular to the optical axis.
These and other objects, structures and advantages of the present invention will be apparent more clearly when the following detailed description of the preferred embodiments is considered taken in conjunction with the accompanying drawings.